184 The Dancing Mouse 



For the investigation of this matter the labyrinth method 

 seemed eminently suitable. The first form of labyrinth 

 which was used in these visual tests appears in ground 

 plan in Figure 23. It was made of ij cm. boards. The 

 length was 52 cm., the width 17 cm., the depth 10 cm. Each 

 of the doorways, / (the entrance), i, 2, 3, and O (the exit), 

 was 5 by 5 cm. The alleys were 2j cm. wide. For this 



FIGURE 23. Labyrinth B. /, entrance; O, exit; i, 2, 3, doorways between alleys. 



width the necessity is obvious from what has already been 

 said of the animal's propensity to whirl on all occasions. As 

 the mice almost never tried to climb up the walls, no cover 

 for the labyrinth was needed. The direct route is indicated 

 by the symbols 7-I-2-3-O. If an error be defined as a choice 

 of the wrong path as the animal progressed toward the exit, 

 five mistakes were possible in the forward course : the first by 

 turning to the left at the entrance ; the second by failing to 

 pass through doorway i ; the third by turning to the right 

 after passing through doorway i ; the fourth by failing to 

 pass through doorway 3, and the fifth by turning to the left 

 after passing through 3. In case the mouse retraced its 

 course, any mistakes made as it again progressed towards O 

 were counted, as at first, no matter how many times it 



